It is nonmetallic and tetravalent âmaking four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen.It is present in all forms of carbon-based life, and in the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen.n combination with oxygen in carbon dioxide, carbon is found in the Earth's atmosphere (approximately 810 gigatonnes of carbon) and dissolved in all water bodies (approximately 36,000 gigatonnes of carbon). Around 1,900 gigatonnes of carbon are present in the biosphere.
The Patient Protection and Affordable Care Act (PPACA), commonly called the Affordable Care Act (ACA) or Obamacare, is a United States federal statute enacted by President Barack Obama on March 23, 2010.
President Obama signed the Affordable Care Act into law in March 2010. This law is intended to make sweeping changes to healthcare in the United States. Many of the lawâs provisions are already in effect, while others will come in the next few years.